Driving mechanism for sewing-machines.



No. 696,933. Patented Apr. 8, i902.

S..BURTON 8:. 0. B. BRUSH.

DRIVIN G MECHANISM FOR SEWING MACHINES.

(Application filed Jan. 26, 1901'. (no 3 Shepts-Shaot I.

No 696,933. Patented Apr. 8, I902.

S. BURTON & G. B. BRUSH. DRIVING IEGHANISIFOB SEWING MACHINES.

I A lication filed Jan. 6, 1901.

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No. 696,933. Patented Apr. 8, I902. S. BURTON & 0. B. BRUSH. DRIVING MECHANISM FOR SEWING MACHINES.

(Application filed Jan. 26, 1901.)

(No Model.)

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STOCKTON BORTON, OF PROVIDENCE, RHODE ISLAND, AND OTIS B. BRUSH,

OF BRIDGEPORT, CONNECTICUT, ASSIGNORS TO WILLCOX & GIBBS SEW- ING MACHINE COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

DRIVING MECHANISM FOR SEWING MACHINES.

SPECIFICATION forming part Of Letters Patent No. 696,933, dated April 8, 1902. Application filed January 26, 1901- Serial No. 44,850. (No model.)

To a. whom it may concern:

Be it known that we, STOCKTON BORTON, a resident of Providence, Rhode Island, and OTIS B. BRUSH, aresidentof Bridgeport, Connecticut, have invented a new and useful Improvementin Driving Mechanism for Sewing- Machines, which invention is fully set forth in the following specification.

This invention has reference to means for to driving the hook or looper shaft of a sewingmachine from the main shaft, and is particularly applicable to machines such as the Willcox & Gibbs lock-stitch machine, which in operation is driven at a very high rate of speed.

The invention comprises certain improved construction and combinations of parts which, together with the utilities thereof, can be most clearly explained in connection with the accompanying drawings, wherein Figure l is a side View of the arm, partly broken away, of a Willcox & Gibbs lockstitch machine. Figs. 2, 3, 4, and 5 are detail views of the lower-pulley guard. Fig. 6 is an end view of the upper or driving pulley. z 5 Fig. 7 shows details of the upperpulley guard. Fig. 8 is a section transverse of the shaft. Fig. 9 is a section lengthwise of the shaft, and Fig. 10 is an elevation illustrating the construction of the lower pulley. Fig. 11 is a rear end viewof the machine with the driven pulley and bearing removed. Fig. 1 2 is a sectional detail of part of the arm. Figs. 13 and 14. are details of a form of pulleyguard different from that illustrated in Figs.

The hollow arm 20 incloses the main or driving shaft 21, from which the hook-shaft 22 is driven through the driving-pulley 23 on the main shaft, the perforated belt 24, and the driven pulley 25. In the form of machine illustrated the hook-shaft makes three revolutions to each revolution of the main shaft, and as the latter is sometimes driven as high as about four thousand revolutions per minute the hook-shaft makes under these conditions twelve thousand revolutions per minute. One of the chief difficulties encountered in constructing a machine capable of running at such high speeds has been to provide efficient and practical means for driving the hook-shaft from the main shaft in the perfect synchronism requisite for accurate work. After much experimentation it has been found that the best results are socured by the use of a belt (of leather or other suitable material) having perforations 26 at equidistant points, these holes registering and engaging with corresponding pins 27 28 on the driving and driven pulleys, respectively. In the use of this mechanism at the high speeds mentioned, which are much beyond those ordinarily practiced by the means of belts and pulleys, it is found that the belt is Very liable to slip off the pins, and thus derange the timing and proper operation of the sewing mechanism. This may be due at times to the catching of the work or some other drag on the hook-shaft. It is also d ue to the momentum of the belt itself and the great centrifugal force developed, causing the belt to bow outward from the pulley on the approaching side thereof. To counteract this difliculty, the driven pulley is according to the present invention provided with a guard. As shown in Figs. 1 and 2,this guard is in the form ofa roller 30, supported on the approaching side of the pulley 25 and having a groove 31 for entrance of the pins 28. This roller is supported by a casting 32 in close contact with the belt 24,

but preferably not touching the latter unless it separates from the pulley. It has been found that the use of a single roller at this point will not always prevent the belt from slipping off its pins. At extremely high speeds the belt after passing the roller 30wil1sounetimes bow out beyond the pins. Therefore, as shown in Figs. 2 and 5, we provide a series of rollers, which inclose about a quarter of the diameter of the pulley. The object of employing guards in the form of rollers is to diminish the friction on the belt when the latter makes contact with the rollers but it has been found quite practical to employ a stationary guard-surface, as shown in Fig. 3. In this figure the guard is a curved metal tongue 32, having the groove or recess 31 for entrance of the pins. This construction has the advantage of simplicity and cheapness and does not cause material friction or wear upon the belt, for the reason that after the latter moves awayfrom the pulley a very slight touch will restore it. As shown in Fig.

4, the guard has both a roller 30 and a stationary guard-surface 32, the latter being an extension of the former. The advantage of this construction is that in most instances the belt would make contact only with the roller, the stationary guard-surface only acting in extreme cases.

Figs. 11, 13, and 14 illustrate another embodiment of this invention, the guard being a curved metal band 33, entirely inclosing the pulley and having horizontal extensions 34, which lie against or in close proximity to the under side of the Work-table. In this case the recess 31 for the pins is cut entirely through the guard.

The belt-guard in any of the forms shown may be attached to a stationary part of the machine in any convenient way or be a part of the sewing-machine table. As shown, the support for the guard is provided with a circular strap 36, which may be in two parts, as in Figs. 2, 5, 14, clamped together by screws 37 around a bushing 38, through which shaft 22 passes. The strap or collar may be in one piece, as in Figs. 3 and 4:, and slipped over the bushing, being held thereto by a setscrew 39.

. When the brake is applied and the machine suddenly checked, the hook-shaft 22 becomes for a moment by its momentum the drivingshaft, and for this reason it has been found necessary to apply a guard to the upper or driving pulley 23. As shown in Figs. 6and 7, this guard is in the form of a curved metal plate 36, attached by a screw 37 to the side of the arm 20. Obviously the guard could be made in one piece with the arm.

The lowerpulley25 beingofsmalldiameter, the belt 24 is bent sharply around it, and hence if the pins 28 were made long enough to take firm hold of the belt they could not enter the holes therein or not without much abrasion of the edges of the holes. To obviate this difficulty, the construction shown in Figs. 8, 9, and 10 is adopted. Pins 28 instead of being fixed rigidly to the pulley work loosely in holes bored through the rim thereof. Within pulley 25 is an eccentric 50, formed on the end of a sleeve 51, through which shaft 22 passes loosely. The heads of pins 28 bear against this eccentric, and consequently as the pulley rotates the pins are thrust outward by the eccentric after they have entered the belt-holes, and when they pass through the plane of the horizon they slip back by gravity or are pushed back by the belt.

In the machine as ordinarily constructed it is a tedious and difficult matter to remove and replace the belt, it being necessary to remove the head of the machine and take out the main shaft. This objection is obviated and other advantages secured by the construction illustrated in Figs. 1, 11, and 12 and described hereinafter, said construction being made the subject-matter of our divisional application, filed November 13, 1901, Serial No.

82,156. As there shown, a circular opening, concentric With the main shaft, is made in the back of the arm or standard 20. Within this opening is fitted a removable plate 54,

which carries the bearing of the main shaft.

To get access to the belt, it is only necessary to detach the hand-wheel 55 and the removable bearing-plate. This exposes the pulley 23, as shown in Fig. 11. The periphery of the circular opening in the arm is provided with notches 56, the same distance apart as the pins 27 on pulley 23. This permits the insertion and withdrawal of the pulley with out making the opening of materially larger diameter than the periphery of the pulley. As is well understood, it is important to make the arm as small in diameter as possible, and inasmuch as the driving-pulley 23 must be two or more times the diameter of the driven pulley any increase in the size of the casing beyond what is necessary to inclose pulley 23 would be very objectionable.

Having now fully described our said invention, what we claim is- 1. The combination with the driving-shaft and hook-shat t, the pulleys having peripheral pins, and the perforated belt, of a belt-guard adjacent to the driven pulley for preventing the belt slipping off the pins.

2. The combination with the hook-shaft and pin-pulley thereon, and with the perforated driving-belt, of a belt-guard having a surface adjacent to said pulley, but normally out of contact with said belt, said surface having a groove or recess for entrance of the IDS.

p 3. The combination with the hook-shaft,

driven pulley thereon having peripheral pins,

and driving-belt having perforations engag ing said pins, of a belt-guard comprising a grooved metal tongue adjacent to said pulley.

4. The combination with the hook-shaft, driven pulley thereon having peripheral pins, and driving-belt having perforations engaging said pins, of a belt-guard, comprising a curved metal plate having a stationary guardsurface extending partly around said pulley, and having a groove or recess for entrance of the pins.

5. The combination with the driving-pulley on the main shaft and the driven pulley on the hook-shaft, said pulleys having peripheral pins, and with the connecting-belt having perforations to engage said pins, of the grooved belt-guard adjacent to said drivingpulley.

In testimony whereof we have signed this specification in the presence of the subscribing witnesses.

STOCKTON BORTON. OTIS B. BRUSH. 

